1. Field of the Invention
This invention generally relates to a damper disk assembly. More specifically, the present invention relates to a damper disk assembly with a dampening mechanism having multiple stages, at least three stages of torsion characteristics.
2. Background Information
A clutch disk assembly used for a clutch of a car has a clutch function of engaging and/or disengaging a flywheel of an engine to a transmission shaft, and a dampening function of absorbing and dampening torsion vibrations transmitted from the flywheel. The clutch disk assembly basically includes a clutch engagement portion, a pair of input plates, a hub and an elastic portion. The pair of input plates is fixedly coupled to the clutch disk. The hub is disposed on an inner circumferential side of the input plate. The elastic portion elastically couples the hub and the input plates together for movement in a rotary or circular direction. Hereinafter, a dampening mechanism includes a pair of input plates, a hub, and an elastic portion.
When the clutch engagement portion is coupled with the flywheel, a torque is inputted to the clutch disk assembly from the flywheel. The torque is transmitted to the hub via the elastic portion, and then is outputted to the shaft extending from the transmission. When a torque fluctuation is input to the clutch disk assembly from the engine, a relative rotation is caused between the pair of input plates and the hub, and the elastic portion is compressed repeatedly in a rotating direction. In addition, the clutch disk assembly typically includes a friction mechanism. The friction mechanism is disposed between the input plates and the hub, and generates a friction resistance when the input plates rotate relatively with respect to the hub. The friction mechanism includes basically a plurality of washers and urging members.
In some conventional clutch disk assemblies, the torsion characteristics are configured to provide four stages for reducing noises and vibrations. The first stage provides a low rigidity, the second stage provides an intermediate rigidity, and third and fourth stages provide high rigidities. For providing the four stages, four kinds elastic members are disposed such that these are successively compressed in accordance with increase in a torsion angle. More specifically, the elastic members for the second, third and fourth stages are disposed in windows formed in a flange of a hub, and are configured to operate in parallel with each other between paired plates.
The friction mechanism is formed of, e.g., a first friction mechanism generating a low hysteresis torque in the first stage and a second friction mechanism which does not operate in the first stage, and generates a high hysteresis torque in the second, third and fourth stages.
According to the above structure, a magnitude of the hysteresis torque rapidly changes in addition to change in rigidity, for example, when the second stage starts (i.e., at a boundary between the first and second stages).
Minute vibrations during idling primarily act in the positive and negative first stages, and are absorbed by characteristics of a low rigidity and a low hysteresis torque. However, the vibrations which operate in the range of the positive and negative first stages may expand to the positive and negative second stages, and the vibrations may be rebounded at the positive and negative stage ends by walls of high hysteresis torques, e.g., in the second stages so that further disadvantageous vibrations (jumping phenomenon) may occur.
In view of the above, there exists a need for a dampening mechanism which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.